El Niño and La Niña cycles offer an opportunity to learn how the ocean and the atmosphere interact over time. Satellite data, combined with measurements from a network of buoys scattered around the Pacific, provide a precise picture of sea level and surface temperature changes. In the images below, colors represent variations in sea level, black areas are land, and grays are polar ice.

El Niño sea level heights
During El Niño, above average sea levels (red and white) are seen in the eastern Pacific Ocean near South America. Below average sea levels (blue and purple) occur simultaneously in the western Pacific.

La Niña sea level heights
During La Niña periods, sea level heights are lower than average (blue and purple) in the eastern Pacific Ocean and higher than average (red and white) in the western Pacific.